Constitutional law professor Bibombe Mwamba is one of the few Zairians whose personal prestige, cloaked in the regalia of officialdom, allows him to speak, with relative candor about a political system that muffles dissent.

Bibombe's causes keep him on a tight schedule, and his proverbial absent-mindedness about appointments forces those interested in seeing him literally to track him down.

Found one recent night in a large, second-floor office in downtown Lubashi, where he was supervising students organizing papers from a human rights symposium held the previous week, Bibombe talked about widespread violations in Zaire's courts, prisons and civilian administration. The abuses, he said, are perpetuated by the country's 30,000-man army.

Above the clatter of typewriters and a hand-cranked mimeograph machine, Bibombe explained that his efforts are directed at drawing the attention of Zairians and international organizations "to the violations, and the government's obligation to protect human rights."

But even Bibombe's criticisms are offered within limits that indicate a certain caution about holding the one-party regime of President Mobutu Sese Seko responsible.

"All of these things have been announced by the president himself," he said. Asked if there were political rights violations in need of investigation in Zaire, Bibombe chose his words carefully.

"All of us are not authorized to give the right answer to this question," he said. "Most of the Third World has a system of presidentialism different from presidentialism in America."

Pinned above Bibombe's heart was the green rectangular pin, engraved with Mobutu's likeness, that denotes membership in Zaire's only legal political party, the Popular Movement of the Revolution.

His recent three-day human rights symposium, during which speakers criticized Zaire's government by citing "hypothetical cases" in a "certain country," was attended by a small group of students, professors and several foreign observers.

The participants voted to seek ways of investigating rights abuses and to establish a national commission on human rights.

"There are many cases of human rights violations here," Bibombe said. Among the areas where he said reforms were needed, Bibombe included:

Courts where judges are "not free from political influence," commonly accept bribes for their decisions and manipulate defense attorneys "by demanding a share of the fees."

Prisons where inmates are subjected to their guards "sadism and intimidation" unless relatives supply bribe money.

Government agencies where civil servants "give hell to the citizens," forcing the poor to "pay them to get public functions done."

The army, whose soldiers roam the countryside indiscriminately "taking things from people by force."

Mobutu has blamed the present situation "on the liquidation of our customs and morals." In 1977, he announced a long list of reforms, most of which have not been acted on, including a national ombudsman office, which he called "the people's eye," to investigate charges of rights violations.

Nothing has been done since, Bibombe said, "because it has been caught up" in party politics. "There are many candidates for ombudsman, there are many ambitions," was all he would say.

Criticism "must stay within the party system," he said. "One uses nuances for expression."